The present invention relates to a scroll compressor for use in a refrigerating cycle for an air conditioner or the like, and more particularly to a scroll compressor lower-priced in structure having good compression efficiency.
Most of recent air conditioners have used a scroll compressor having good compression efficiency. FIG. 6 shows its one example. This scroll compressor 1 has a cylindrically-formed hermetic shell 2, and its interior is partitioned into a refrigerant discharge chamber R1 and a driving chamber R2 by means of a main frame 4.
Within the refrigerant discharge chamber R1, there is housed a refrigerant compressing section 3 comprising a fixed-scroll 31 having voluted scrolled-wrap 312 on a base plate 311 and an orbiting-scroll 32 to be driven by an electric motor engaged.
An electric motor is housed within the driving chamber R2 although not shown, and a predetermined amount of lubricating oil is stored. One end of a driving shaft 6 of the electric motor penetrates the main frame 4, and a crankshaft 61 at its tip end is connected to a boss 323 on the back surface of the base plate 321 of the orbiting-scroll 32.
When the scroll compressor 1 is driven, low-pressure refrigerant, which has finished the work in the refrigerating cycle, is sucked in from an outer periphery side of a compressing chamber 33 through a refrigerant suction pipe 21, is more compressed as it goes toward the center of the vortex, and is discharged into the refrigerant discharge chamber R1 from a discharge port 34 provided at the center as high-pressure refrigerant. The high-pressure refrigerant thus discharged is conducted into the driving chamber R2 through a by-pass pipe 35, and thereafter, is supplied from a refrigerant discharge pipe 22 again into the refrigerating cycle.
At the time of this refrigerant compression operation, pressure is always applied onto the orbiting-scroll 32 from within the compressing chamber 33 in a direction that departs from the fixed-scroll 31. Further, as it goes from the outer periphery side (low-pressure refrigerant suction side) of the vortex toward the center, the pressure has a pressure gradient to shift from low pressure to high pressure. Therefore, it is necessary to prevent the orbiting-scroll 32 from being lifted by applying such back-pressure as to resist the pressure to the orbiting-scroll 32.
In this conventional example, in order to apply back-pressure corresponding to the pressure gradient to the orbiting-scroll 32, on the back surface side of the orbiting-scroll 32, there is provided a thrust ring 5 to thereby divide into a first back-pressure chamber LR (low-pressure side) on the peripheral portion side and a second back-pressure chamber HR (high-pressure side) on the central portion side. Thereby, to the second back-pressure chamber HR, the high pressure within the driving chamber R1 is applied, while to the first back-pressure chamber LR, lower pressure on the low-pressure refrigerant side than the second back-pressure chamber HR is applied.
At the time of starting or the like, however, since no high pressure is developed within the hermetic shell 2, no appropriate back pressure is applied to the orbiting-scroll 32, but a compression failure may possibly be caused. Thus, in order to regulate a movable range of the orbiting-scroll 32 in the axial direction, the main frame 4 has been provided with a regulation surface 41 to physically regulate the movable range of the orbiting-scroll 32 for preventing any compression failure.
Also, apart from this, there has also been proposed a type in which, on the main frame 4 opposite to the back surface of the thrust ring 5, there is provided a second regulation surface 411 to indirectly regulate the movable range of the orbiting-scroll 32 in the axial direction through the thrust ring 5. In either of these types, however, there has been a problem that it is necessary to individually machine each regulation surface 41, 411 with high precision, and as a result, the cost will become higher.
The present invention has been achieved in order to solve the above-described problem, and is aimed to provide a low-cost scroll compressor which is stable even in an operating state with a small difference in pressure such as during starting by indirectly regulating the movable range of the orbiting-scroll through the thrust ring.
In order to attain the above-described object, a scroll compressor according to the present invention in which between the base plate back surface of the orbiting-scroll and the main frame, there is provided a thrust ring, and in which one end surface of the thrust ring seals in slidable contact with the base plate back surface of the orbiting-scroll to thereby partition the base plate back surface of the orbiting-scroll into a plurality of pressure space, is characterized in that the thrust ring has a main body of a ring to be fitted along an inner peripheral surface of the main frame, and a flange portion having a larger outer diameter than an outer diameter of the inner peripheral surface, and that between the base plate back surface of the orbiting-scroll and a regulation surface to be used in common with a grind surface of an Oldham-coupling ring provided on the main frame side, there is interposed the flange portion, whereby the movable range of the thrust ring in the axial direction is regulated.
According to this invention, any new regulation surface is not provided on the main frame side unlike-the conventional case to restrict the movable range of the orbiting-scroll, but the movable range of the orbiting-scroll is indirectly regulated through the regulation surface of the thrust ring, whereby the fabrication cost of the main frame can be reduced.
The regulation surface depth of the main frame and the thickness of the flange portion of the thrust ring are selected for fitting, whereby it becomes possible to control the movable range, and the movable range can be regulated with higher precision at low cost. Even in this structure, the orbiting-scroll is capable of performing sufficiently stable movement, but in order to bring more stability, the flange portion of the thrust ring has preferably as large outer diameter as possible. In this case, under an operating pressure condition, in which a force in a direction that depresses the orbiting-scroll with respect to the fixed-scroll becomes substantially equal such as, for example, during starting, the force in the direction that depresses is capable of reducing a so-called overthrow motion in which the orbiting-scroll conducts like a falling piece because of fluctuation during one rotation of the orbiting-scroll.
On a grind surface of the flange portion which slidably contacts the base plate back surface of the orbiting-scroll, there is provided an annular groove, and further a communicating groove or a communicating hole which communicates the groove to suction pressure space formed on the outer periphery of the thrust ring is preferably formed along the radial direction of the flange portion. In this case, it is possible to form the suction pressure space between the grind surfaces with the orbiting-scroll, thus making it possible to prevent the thrust ring from departing from orbiting-scroll.
On the base plate back surface of the orbiting-scroll which slidably contacts the flange portion, there is provided an annular groove; further it may be possible to form a communicating groove or a communicating hole, which communicates the groove to suction pressure space formed on the outer periphery of the thrust ring, along the radial direction of the orbiting-scroll; it may be possible to form an annular groove on a grind surface between the thrust ring and the orbiting-scroll, and further to provide the groove with a communicating hole for penetrating in the axial direction of the thrust ring.
Also, in addition to the forgoing, it may be possible to provide the grind surface between the thrust ring and the orbiting-scroll with an annular groove, and to cause the groove to continuously or intermittently communicate to a key way which fits in an Oldham-coupling ring key on the base plate back surface of the orbiting-scroll.